Debt-to-Income Ratio Explained: How Lenders Judge Your Mortgage
Your debt-to-income ratio is one of the first things a mortgage lender checks. This guide explains what DTI is, how to calculate it, what counts as a good ratio, and how to improve yours before applying for a home loan.
When you apply for a mortgage, lenders don't just look at your income — they look at how much of it is already spoken for. Your debt-to-income ratio (DTI) is one of the first numbers they check, and it can make or break your application. This guide explains what the debt-to-income ratio is, how to calculate yours, what counts as a good number, and how to improve it before you apply.
DTI works hand in hand with mortgage affordability, which we cover in our guides on how much mortgage you can borrow and how much house you can afford. Let's break down the ratio itself.
What is a debt-to-income ratio?
Your debt-to-income ratio is the percentage of your gross monthly income that goes towards paying debts. Lenders use it to judge whether you can comfortably take on a mortgage payment on top of your existing commitments. The lower your DTI, the more room you have — and the more confident a lender is that you can afford the loan.
There are usually two versions lenders look at:
- Front-end DTI — housing costs alone (mortgage, taxes, insurance) as a share of income.
- Back-end DTI — all debt payments, including housing plus car loans, credit cards and student loans.
How to calculate your debt-to-income ratio
The calculation is simple. Add up your total monthly debt payments, divide by your gross monthly income, and multiply by 100 to get a percentage:
DTI = (Total monthly debt payments ÷ Gross monthly income) × 100
Include recurring debts like loan repayments, credit card minimums, car finance and the proposed mortgage payment. Don't include everyday living costs like groceries, utilities or subscriptions — DTI is about debt, not general spending.
Worked example
Suppose your gross monthly income is $5,000, and your monthly debts are:
| Debt | Monthly payment |
|---|---|
| Proposed mortgage | $1,200 |
| Car loan | $300 |
| Credit card minimums | $150 |
| Total | $1,650 |
DTI = ($1,650 ÷ $5,000) × 100 = 33%. That's a healthy back-end ratio that most lenders would be comfortable with.
What is a good debt-to-income ratio?
As a general guide:
- 36% or below — considered good; lenders see you as low risk.
- 37% to 43% — acceptable to many lenders, though it may limit your options.
- Above 43% — often the upper limit for many mortgages; borrowing gets harder.
This ties directly to the 28/36 rule used by US lenders, which we explain in our guide to how much house you can afford. A lower DTI not only improves your chances of approval but can also unlock better interest rates.
How to improve your debt-to-income ratio
If your DTI is too high, there are two levers: reduce your debt payments, or increase your income. The faster route for most people is cutting debt:
- Pay down existing debts — clearing a credit card or car loan removes that payment from the calculation. Our guides on paying off credit card debt fast and the snowball vs avalanche methods show how.
- Avoid new debt before applying — a new car loan right before a mortgage application can push your DTI over the limit.
- Boost your income — a pay rise, bonus or second income lowers the ratio from the other direction.
Why lowering DTI is worth the effort
Reducing your debt-to-income ratio before you apply does more than get you approved. It can qualify you for a larger mortgage, secure a lower interest rate, and leave you with more breathing room in your monthly budget after you move in. Given how much interest a mortgage accrues over decades — as our amortization schedule guide shows — a better rate is well worth a few months of debt reduction first.
Frequently asked questions
What is a debt-to-income ratio?
It's the percentage of your gross monthly income that goes toward debt payments. Lenders use it to assess whether you can afford a mortgage on top of your existing commitments. A lower ratio is better.
How do I calculate my debt-to-income ratio?
Add up your total monthly debt payments, divide by your gross monthly income, and multiply by 100. For example, $1,650 of debt on $5,000 income is a 33% DTI.
What is a good DTI for a mortgage?
36% or below is considered good and low-risk. Many lenders accept up to about 43%, but above that, getting a mortgage becomes harder and rates may be less favourable.
Does DTI include rent or living costs?
DTI includes debt payments like loans, credit cards and the proposed mortgage. It excludes everyday living costs such as groceries, utilities and subscriptions, which are not classed as debt.
How can I lower my debt-to-income ratio?
Pay down existing debts (especially credit cards and car loans), avoid taking on new debt before applying, and increase your income where possible. Clearing a monthly payment directly reduces your ratio.
This article was last reviewed in 2026. Figures are illustrative for guidance only and are not financial advice. Lending criteria vary between lenders.